IBM’s Watson AI software is best-known for winning at “Jeopardy!” in 2011. (Credit: IBM) The latest multimillion-dollar tech challenge – known as the IBM Watson AI XPRIZE – will be aimed at encouraging collaboration between humans and artificial intelligence software to solve the world’s big problems. But it’s not yet clear who will sign up for the $5 million competition, in part because IBM’s Watson program is already one of the contestants in a much bigger, multibillion-dollar AI race.Today’s announcement, made at the TED2016 conference in Vancouver, B.C., adds artificial intelligence to an XPRIZE list that also spotlights ocean discovery, moon exploration, carbon recycling, medical diagnostic devices, educational software and much, much more. “Our hope is that the teams will show how we can apply AI to the world’s great challenges,” Stephanie…